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The preparation of activated carbons from bean pods waste by chemical (K(2)CO(3)) and physical (water vapor) activation was investigated. The carbon prepared by chemical activation presented a more developed porous structure (surface area 1580 m(2) g(-1) and pore volume 0.809 cm(3) g(-1)) than the one obtained by water vapor activation (258 m(2) g(-1) and 0.206 cm(3) g(-1)). These carbons were explored as adsorbents for the adsorption of naphthalene from water solutions at low concentration and room temperature and their properties are compared with those of commercial activated carbons. Naphthalene adsorption on the carbons obtained from agricultural waste was stronger than that of carbon adsorbents reported in the literature. This seems to be due to the presence of large amounts of basic groups on the bean-pod-based carbons. The adsorption capacity evaluated from Freundlich equation was found to depend on both the textural and chemical properties of the carbons. Naphthalene uptake on biomass-derived carbons was 300 and 85 mg g(-1) for the carbon prepared by chemical and physical activation, respectively. Moreover, when the uptake is normalized per unit area of adsorbent, the least porous carbon displays enhanced naphthalene removal. The results suggest an important role of the carbon composition including mineral matter in naphthalene retention. This issue remains under investigation.

The wetting of ultrathin films of polystyrene on the hydrophilic surfaces of mica and silicon oxide was studied by atomic force microscopy. After annealing, the surfaces were covered with a homogeneous, continuous polystyrene film of roughly 1 nm thickness. On top of this film, polystyrene droplets with microscopic contact angles of 7°-16°were observed. After exposure to an oversaturated water vapor, the continuous polystyrene film disintegrates and dewets the surfaces. Polystyrene structures on silicon oxide indicate a homogeneous dewetting process starting from few nucleation sites. On mica the density of nucleation sites for water is much higher and the polystyrene dewets the surface in an inhomogeneous process. The structural changes observed imply that ultrathin polystyrene films are highly mobile in the presence of water.

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A carbon foam using coal tar pitch as precursor was prepared and investigated as support for titanium oxide for the photocatalytic degradation of phenol. The performance of the carbon foam/titania composite was compared to those of unsupported titania and other activated carbon composites from the literature. The photodegradation rate of phenol over the catalysts under UV illumination was fitted to the Langmuir-Hinshelwood model; data showed that the apparent rate constant of the carbon foam supported titania was almost three times larger than that of bare titania, and comparable to that of other carbon supported composites. Considering the low porous features of the carbon foam, this suggests that large surface area supports are not essential to achieve high degradation rates and efficiencies. Moreover, when titania is supported on the carbon foam large amounts of catechol are detected in solution after UV irradiation, indicating a better degradation efficiency.

Adsorption of m-aminophenol and p-nitrophenol from aqueous solution on activated carbon synthesized on the base of industrial by product (coal tar pitch) and furfural was investigated.The adsorption capacity of the activated carbon and its oxidized modification is related to the surface area and composition of the prepared materials, as well as to the nature of the adsorbents. Despite the moderate porosity, the prepared materials display adequate adsorption capacity towards the investigated aromatic compounds. Both adsorbates show higher affinity towards the hydrophobic carbon, confirming that the retention mechanism occurs via nonspecific interactions between the electronic density of the adsorbent and the aromatic pollutants. Electrostatic interactions may also appear depending on the solution pH and the charge distribution of the carbons; we have observed that this parameter has a strong influence on the final performance of the oxidized carbon, where repulsive interactions that reduced the uptake of the carbon were found to appear within a larger pH range.

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